The invention relates to a device for the feed of harness elements, in particular of healds or droppers, for their subsequent separation in a separating station of a drawing-in machine, the said device having at least one feed rail, on which can be arranged the harness elements, such as healds or droppers, which, in this case, engage with guide elements, such as, for example, guide loops, around the at least one feed rail.
To prepare for weaving, harness elements, such as healds and droppers, must be drawn onto the warp threads by means of a warp drawing-in machine. This is carried out, as a rule, by feeding a stack of the respective harness elements to a separating station. Separating stations of this kind for healds or droppers are already known per se. Although the separating stations for healds differ, as a rule, from those for droppers in their design, they have in common the fact that they in each case extract one harness element, specifically the foremost element in each case, from the harness element stack. A transport means then transports the individual harness element further to another location on the warp drawing-in machine, at which the harness is arranged on a warp thread. In order to ensure that a warp drawing-in machine operates faultlessly, it is therefore important that the harness elements are individually separated from the corresponding stack reliably and at the intended time by the respective separating station and made available for further transport. Within the scope of the present invention, then, it became apparent that the reasons for unsatisfactory operating reliability of separating stations are to be found in the means for feeding to the separating stations.
Devices for feeding healds to a separating station, the healds being guided on a horizontally oriented feed rail, are already known. In order to generate at the separating station a pressure force which is advantageous for the reliable pick-up of individual healds, in the feed device already known, for example from WO 92/05303, a pneumatically actuated presser presses against the heald stack. Since the pneumatically actuated presser is absolutely essential in this device, the design is, on the one hand, comparatively complicated. It became apparent, on the other hand, that, in spite of the presser, the operating reliability of the feed device is not entirely satisfactory.
A disadvantage of the devices already known for feeding droppers is that, likewise, there is no constant pressure force prevailing on the droppers at the separating point. Thus, when a dropper stack is being worked through in a separating station, there are not any constant conditions for separating the foremost droppers in each case. This may be the cause of malfunctions in the automatic separation of the droppers.
The object on which the invention is based is, therefore, to provide devices for feeding harness elements, such as either healds or droppers, into a separating station, the operating reliability of which is improved, as compared with corresponding devices already known.
In a device of the type mentioned in the introduction, this object is achieved, in that the at least one feed rail of the device has an inclination relative to a horizontal, with the result that a slope descending force acts on the harness elements which are arranged with their guide loops preferably directly on the feed rail, as it is mentioned in the combination of features of claim 1.
An important advantage of this solution is that, by virtue of the inclination of the rail, a slope descending force of the harness elements arranged on the feed rail is generated and can be utilized for conveying the harness elements in the direction of the separating station and for pressing the harness elements onto the separating station. It is thereby possible, irrespective of the size of the stack of harness elements, to bring about relatively uniform conditions in respect of the harness elements in the separating station. This contributes to achieving a high degree of operating reliability in the individual separation of the harness elements.
It has proved advantageous, particularly in connection with the separation of healds, if the slant or inclination of the rail in the direction of the separating station corresponds approximately to the coefficient of static or sliding friction between the feed rail and the healds arranged on the rail. A pressure force essentially independent of the weight of the heald stack, for pressing onto the separating station, can thus be generated. In order to ensure this, it is preferable if the angle of inclination of the rail deviates by at most 30%, particularly preferably by at most 20%, from that angle of inclination at which an equilibrium prevails between the weight force of the heald stack and the static or sliding frictional force which is established between the healds and the guide rail during the separation process respectively the feeding of the healds. This condition can be expressed as a formula as follows:
Fr≅Fn*xcexcc,
in which: Fr=Static frictional force;
xcexcc=Coefficient of static friction between the rails and the healds,
Fn=the component of the weight force FG which is oriented parallel to a perpendicular to the oblique plane, with Fn=FG*cos xcex1, and xcex1=inclination of the oblique plane relative to a horizontal.
In a further advantageous refinement according to the invention, the device has a slide which presses against the heald stack. Moreover, if the feed rail is provided with the above-described angle of inclination at which an equilibrium at least approximately prevails between the sliding or static frictional force e and the slope descending force, the healds come to bear with an essentially constant pressure force at the separating station. This pressure force arises from the weight force of the slide or of another pressure element and is independent of the weight of the heald stack and therefore of the number of healds.
Preferred refinements of the invention may be gathered from the description blow.
Preferred refinements of the invention may be gathered from the dependent claims.
The invention is explained in more detail with reference to the exemplary embodiments illustrated diagrammatically in the figures of which: